The optimal methods, environmental effects and cost-effectiveness of mass air flow and laminar air flow in animal quarantine and isolation facilities will be determined through controlled prospective studies. Infection studies with polyoma virus and Proteus mirabilis will determine optimum type of cage, rack spacing, velocity, animal density and cost-effectiveness for mass air flow using an air velocity of 30 ft/min. and laminar air flow using an air velocity of 100 ft/min. Physiological studies will determine the effect on growth of mice. Environmental studies will measure accumulation of gases in the atmosphere and inside the cages of the study and control rooms. Temperature, relative humidity, and noise levels will also be monitored. Cost analysis will include a determination of the number of man hours required to maintain the mass air flow room and the laminar air flow rooms; the permissable animal density, and the energy in kilowatt hours required to operate the fans and air conditioning system. All studies will utilize groups of mice amenable to statistical analysis. Attempts will be made to isolate polyoma virus from the air and to determine the effect of sampling, collection media and concentration on the virus. Engineering studies will be performed to determine and quantitate the air movement into and around individual cages. The total cost of this proposal is equivalent to one medium size mass air flow room. The results of these studies will have practical and immediate applications to the increasing number of quarantine, isolation and other animal facilities being equipped with mass air flow, and in planning future facilities.